We are examining a number of cobalt-molybdenum carbonitrides as possible catalysts for reactions that produce nitrogen-containing organic molecules. There is good evidence that these can cycle nitrogen from a gas stream into their crystal lattice and back again. This experiment investigates the formation and transformation of such carbonitrides under various gaseous environments to understand the conditions under which anions enter or leave the different lattice sites that they can occupy. The strong neutron scattering from carbon and nitrogen, with good contrast between them, makes neutron diffraction ideal for this purpose. The success of this experiment will allow us to predict conditions under which catalytic reactions are likely to occur most readily.